/*********************************************************************************
 *      Copyright:  (C) 2025 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  signal.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(22/03/25)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "22/03/25 14:04:13"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

int g_child_stop = 0;
int g_parent_run = 0;

void sig_child(int signum)
{
	if(SIGUSR1 == signum)
	{
		g_child_stop = 1;
	}
}

void sig_parent(int signum)
{
	if(SIGUSR2 == signum)
	{
		g_parent_run = 1;
	}
}

int main(int argc, char **argv )
{
	int 			pid;
	int				wstatus;

	signal(SIGUSR1, sig_child);
	signal(SIGUSR2, sig_parent);

	if((pid=fork()) < 0)
	{
		printf("Create child process failure: %s\n", strerror(errno));
		return -2;
	}
	else if(pid == 0)
	{
		printf("Child process start running and send parent a signal\n");
		kill(get(pid), SIGUSR2);

		while(!g_child_stop)
		{
			sleep(1);
		}

		printf("Child process receive signal from parent and exit now\n");
		return 0;
	}

	printf("Parent hangs up untill receive signal from child!\n");
	wihle(!g_parent_run)
	{
		sleep(1);
	}


	printf("Parent start running now and send child a signal to exit\n");
	kill(pid, SIGUSR1);

	wait(&wstatus);
	printf("Parent wait child process die and exit now\n");

	return 0;
}
